Mongoose QuickSample
Quick and efficient random sampling of records utilizing a seed field.
Rather than relying on the painfully slow $sample
aggregation stage, Mongoose QuickSample embeds a simple numeric __seed
field in your schemas that is autopopulated with a random number between 0 and 1.
You can sort by this field using the quickSample
aggregation method or query helper method, and the seed will be automatically updated after each sample.
The __seed
field is indexed by default, which results in an extremely fast random sample.
Install via npm (or your favourite package manager)
npm install mongoose-quick-sample@latest
Import and install the Mongoose plugin
import mongoose from "mongoose";
import { QuickSample } from "mongoose-quick-sample";
// Enable per-schema (recommended)
schema.plugin(QuickSample.Plugin);
// Enable globally
mongoose.plugin(QuickSample.Plugin);
Note: If you enable QuickSample globally, every record in every collection will gain a __seed
field. So be warned!
You can use quickSample
on aggregations and standard queries. Give it a go!
// Returns 10 random users
const users = await UserModel
.find()
.quickSample(10);
// Returns 10 random posts by the 10 random users
const posts = await PostsModel
.aggregate([
{
$match: {
user: {
$in: users.map(user => user._id)
}
}
}
])
.quickSample(10);
[!NOTE] When you run your first
quickSample
on a given schema, mongoose will automatically populate all documents in the collection that do not yet have a__seed
field.If your collection is particularly large or you'd rather do this yourself, you can set
autoInsert
to false in the plugin options (see below).
The QuickSample plugin accepts an options
object that inherits properties from a numeric schema type. That is, it expects you to be configuring the __seed
path in the schema.
The one exception to this is the autoInsert
property, which disables the behaviour of automatically populating missing __seed
fields across your whole collection.
mongoose.plugin(QuickSample.Plugin, {
// Let me sow my own oats!
autoInsert: false,
// Typical mongoose numeric type props
default: () => weightedRand({ 0: 0.3, 0.5: 0.6, 1: 0.1 }),
index: false,
});